Jack



H. OLIVIER' JACK Filed Oct. 30, 1958 May 3, 1960 United States Patent JACK Henri Olivier, Neuilly-sur-Sene, France Application October 30, 1958, Serial No.'77l,855

Claims priority, application France December 16, 1957 2 Claims. (Cl. 254-105) My invention has for its object a hydraulic jack, provided with mechanical reciprocating speed-reducing means.

Conventional hydraulic jacks are subjected to pressure by a pump and the number of the parts constituting them is thus comparatively high, which makes their execution expensive.

Now, my invention has for its object to reduce the number of parts of the jack and pump unit and, conse quently, the cost price, this being obtained by making the jack piston operate alternatingly as a part of the pump and as a part of the jack; but since the reduction in the power required cannot be obtained through differences in the diameter of the piston and in the bore of the cylinder, a mechanical control should be obtained.

My invention has thus for its object a yhydraulic jack, the cost price of which is lower than that of the jacks proposed hitherto and it has also for its object a reduction in the bulk of the jack.

According to my invention, the hydraulic jack includes a jack and pump unit and, more speciiicalli/it includes a telescopic cylindrical chamber containing a body of oil and the lower section of which forms a piston subjected to a reciprocatory movement by any suitable means, while the upper section of said chamber is capped by a cylinder sliding over it and forming the jack ensuring a rising movement of the load, the lower section of the chamber engaging slidingly a cylinder inserted in an oil container. A ball valve ensures the admission of the oil from the container into the last-mentioned cylinder, while a spring-urged needle valve controlled by a penal controls the return of oil into the container and a second ball valve controls the entrance of oil into the pistonforming chamber.

According to a preferred embodiment, the mechanical means providing for the reciprocation of the piston-forming chamber section are constituted by a control lever which is pivotally secured to the jack body and is provided with a fork engaging two alined transverse stub shafts rigid with the piston and the outline of which is advantageously such as will ensure the speed reduction and the modiiication of the piston stroke which may be required.

I will now describe my invention with further detail, reference being made to the accompanying diagrammatic drawing given by way of example and the single ligure of which is a vertical sectional View of an improved jack according to my invention.

As illustrated, a cylinder A forming the raising member for the load caps an elongated hollow piston B constituted by an oil-containing metal sheath. Said piston sheath is closed at its lower end by a plug D provided with an axial port forming a seat for a ball C resting freely on the latter. The lower end of the piston B slides inside a cylinder E fitted inside the container F closed in its turn at its lower end by a further plug G also provided with an axial port, the upper end of which forms a seat for a ball H.

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A control lever l pivotally secured at l to the jack body EF is rigid with a fork K engaging two` aligned stub `shafts L including rollers adapted to reduce friction on the fork and secured to the outer wall of the iston B along a diameter of a cross-section of the latter. The fork arms have a shape designed so that it is possible to obtain the desired reduction of speed and modification ot' the piston stroke.

A needle Valve M urged ontosits seat by a spring N closes a port provided in the wall of the cylinder E and opening into an vannular groove formedin the inner wall of said cylinder. The spring N acting on the needle valve is fitted between a collar O rigid with the latter and the corresponding end Aof a plug vfitted in the wall of the container F. Abell crank secured at Rv Ito the container Wall F and controlled by a pedal acts on the needle valve M, said pedal being adapted to shift the needle valve rearwardly through the plug against the action of the spring N, which allows a return into the container of the oil out of the cylinder E and also of the oil contained inside the piston when the groove inside the cylinder E registers with a further port T formed in the wall of the sheath forming the piston B.

The iuidtightness between the piston sheath B and the two cylinders A and E is ensured by packing rings S.

The operation of the arrangement is as follows:

At the start, the jack being in its lower-most position, the piston sheath B, the cylinder E and the container F are filled with oil. Upon moving the control lever'l to the right as shown in the drawing the fork K raises the piston sheath B which latter raises the cylinder A and, consequently, the load.

During this raising of the piston and simultaneously therewith, the ball C engages its seat by reason of the reduction in pressure produced underneath the plug D closing the piston B with 'reference to the cylinder E and, on the contrary, said reduction in pressure raises the ball H, so that vthe oil `from the container is sucked in and fills the space between the bottom of the piston and the bottom of the cylinder E.

This being done, upon movement of the control lever l to the left as shown in the drawing, the fork lowers the piston sheath B, so that the ball H returns on its seat, while the ball C rises and allows the oil to pass inside the piston B, so as to form a column of liquid under pressure which holds the upper cylinder A in the position assumed lby it before the lowering of the piston sheath, prior to the next raising thereof.

The operation may be repeated so as to make the oil raise each time the load by an elementary stroke equal to the stroke travelled over by the fork.

0f course, any other reciprocating control system operated by hand or by a power unit may ybe substituted for the control lever I.

The return of the apparatus into its lower inoperative position is performed by depressing the pedal-controlled bell crank, so as to urge the needle valve M back away from its seat, the `sheath B lbeing in its lowermost position.

It should be remarked that the secure holding of the load in its raised position is actually obtained by the hydraulic column enclosed inside the metal sheath, 'the piston B cooperating with the cylinder A when the latter has been raised.

Obviously, my invention is not limited to the preceding disclosure and to the embodiment illustrated. in fact, it covers all the modications thereof falling within the scope of the accompanying claims.

What claim is:

1. A jack comprising an oillled telescopic pistonorming chamber including an upper section adapted to carry a load and a lower section, means controlling the Vertical reciprocating movements of the lower section, a

cylinder inside which the lower section of the pistonforming chamber is adapted to slide vertically and the bottom of which forms with the bottom of said lastmentioned chamber `an intermediate chamber of varying vol- Vurne, an oil container inside which said cylinder is rigidly secured, the sidewalls ofthe lower section of the pistonforming' chamber and of the cylinder being provided with ports adapted to register for a predetermined lower position of the lower section of the piston-forming chamber inside the cylinder to allow the oil to return ont of the lower section into the container, a ball vave tilted in the bottom of the Vlower section of the piston-forming chamber and adapted to open upon downward movement of said lower section to allow entrance Vof the oil from the intermediate chamber `into said lower section and thereby elect raising of the upper lsection or" the piston4 forming chamber with reference to the lower section and a second ball `valve tted in the bottom of the cylinder and controlling the connections between the oil container and the intermediate chamber and adapted to open upon raising of lthe lower section of the piston-forming chamber to allow the oil to flow from Vthe container into the intermediatechamber to raise bodily the two sections of the piston-forming chamber, a needle valve control- Y ling the port in the cylinder, a spring urging the needle valve into its port-closing position and means for urging the needle valve out of its closing position into its operative port-uncovering position against the action of the spring.

2. A jack comprising an oil-filled telescopic pistonforming chamber including an upper section adapted to carry a load and a lower section, a cylinder inside which the lower section of the piston-forming chamber is adapted to slide vertically and the bottom of which forms with the bottom of said last-mentioned chamber an intermediate chamber of varying volume, an oil container 'inside which said cylinder is rigidly secured, a control lever pivotally secured to the container and cylinder system and including a `fork 'extending to either side of the lower section of the piston-forming chamber, two aligned stub shafts extending diametricaily outside the lower section of the piston-forming chamber and adapted to be engaged by the fork, to provide `a Vertical reciprocation of said lower'section upon actuation ofA the lever with a predetermined speed reduction over a predetermined height, a. ball valve fitted in the bottom of the lower section of the piston-forming chamber and adapted to open upon downward movement of said lower section to allow entrance of Vthe oil from the intermediate chamber into said lower section and thereby effect raising of the upper section of the piston-forming chamber with reference to the lower section and a second ball valve tted in the bottom cf the cylinder and controlling the connections between the oil container andthe intermediate chamber and adapted to open upon raising of the lower section of the piston-forming chamber to allow the oil to ow from the container into the intermediate chamber to raise bodily the two sections of the piston-forming chamber.

References Cited in the file of this patent FOREIGN PATENTS 166,360 Australia Dees 19, 1955 

